Clear and bold mark WP #181 'S' stamped on an ID seal.

This is one of the only three larger floats identified with the WP #181 maker's mark.  It measures 33 1/2 inches in circumference or almost 11 inches in diameter.

In Walt Pich's 'Glass Ball Marks' book, he states, "Only one float has been identified on Pacific beaches; none have been found in Japan."  He describes it as an "10-inch diameter, dark green ball found on the central Oregon coast in the 1960's."

I found a second 11 inch float with mark WP #181 on eBay in 2011.  Mine is only one that's blue-green in color.

In 2021, a third large float with mark WP #181 was found in Japan.  It measures 10.7 inches according the Steve Bradford.  It's a green colored float but I wouldn't describe it as dark green color (as Walt describes the float in his 'Marks' book).

Information about the rarity of floats can change quickly, but these floats seem pretty rare from what I currently know.